FRANKFORT, Ky. — The speaker of Kentucky’s House of Representatives has launched a formal investigation of the state’s Republican governor, appointing a bipartisan committee to probe whether Matt Bevin broke the law while trying to convince Democrats to switch parties in the last legislative chamber in the South not controlled by the GOP.

Democratic Speaker Greg Stumbo said the committee will have the power to subpoena witnesses and to take testimony under oath, and will include three Democrats and two Republicans.

“We’re not asking them to find anything except the truth,” Stumbo said.

But GOP leaders say one of the Republican appointees — Rep. David Floyd of Bardstown — will not participate in what they’re calling an effort to smear Bevin. The other, Rep. Jim Stewart, did not return a call seeking comment.

As Stumbo sought Republican buy-in before announcing the probe, he left a voicemail on Floyd’s cellphone Monday downplaying his allegations against the governor, saying they are “probably not as bad as maybe it was portrayed.”

Bevin’s office released that voicemail on Wednesday, saying it is evidence Stumbo created the committee solely for political reasons as Democrats are defending a slim majority in next month’s elections.

“Ladies and gentlemen, this is a political farce,” said Blake Brickman, Bevin’s chief of staff.

The focus of Stumbo’s inquiry is whether Bevin delayed a road project in state Rep. Russ Meyer’s district as punishment for Meyer refusing to switch parties. The project had been approved by former Democratic Gov. Steve Beshear. When the Bevin administration delayed the project, it triggered a $625,000 penalty taxpayers had to pay the contractor.

Bevin’s transportation officials said the project had to be delayed because the state did not own the property needed to begin construction. They said the project should never have been approved until the state had secured the land, and they blamed former administration officials for rushing the project through in the final month of Beshear’s term.

Stumbo released documents Wednesday indicating the landowner requested a sale price of $434,000 for the property while the state was only willing to pay $225,000.

“Instead of paying him, and we don’t know why they didn’t pay him, they went ahead and paid $625,000 of taxpayers’ money to postpone the contract. That raises serious questions,” Stumbo said.

Brickman defended the decision to delay the project, but referred questions about the documents to the state Department of Transportation. A spokesman for the department did not immediately respond to a request for comment.

House Republican Floor Leader Jeff Hoover questioned Stumbo’s authority to appoint the committee and its ability to issue subpoenas. Stumbo, however, noted he has appointed similar committees in the past. In 2013, he created a panel to investigate sexual harassment allegations against former Democratic state Rep. John Arnold. That committee eventually voted 3-2 along party lines to end its inquiry without issuing a report, saying it lacked the authority to punish Arnold since he had resigned.

This is the second time this year the leader of a major political party has launched a formal investigation into the leader of the opposing party. In July, Bevin hired a private law firm to scrutinize a $3 million no-bid contract issued by Beshear as well as reports of state workers being forced to make political donations to Democratic candidates and causes.

Democrats have called Bevin’s investigation an “abuse of public power,” but have defended Stumbo’s inquiry as an honest fact-finding mission. Republicans have criticized Stumbo’s investigation, while applauding Bevin’s probe as a search for truth.

Both investigations come amid a fierce battle over control of the state legislature. Democrats are protecting a 53-47 majority in the House while Republicans are furiously trying to pick up four seats to win a majority for the first time since 1920.